You might get more useful help by asking about installing Photoshop on a Windows 8 computer in a forum dedicated to Photoshop instead of an RV forum.
Adobe forums. You haven't even mentioned what version of Photoshop you are trying to install so it would be difficult for us to give any useful help.
Have you tried using your favorite search engine to find Photoshop specific help?
What makes you think it's a Windows 8 problem?
I suspect you may have a virus/malware. I have never had little squares pop up asking me to buy things I don't want on any of the computers I use Win 8 on.
If people could just get past the Start screen they would realize that Win 8 really isn't that radically different from Win 7.